1. Field of the Invention
The present invention relates generally to a computer implemented method, a computer program product, and a data processing system. More specifically, the present invention relates to a computer implemented method, a computer program product, and a data processing system for intelligently propagating link status information received by a blade server to the various ports of an embedded multi-port switch.
2. Description of the Related Art
The use of server computers as devices within communications networks is well known in the art. A server is hardware that makes available file, database, printing, facsimile, communications or other services to client terminals/stations with access to the network the server serves. When the server permits client/terminal station access to an external communications network, it is sometimes known as a gateway. Servers are available in different sizes, shapes and varieties. Servers may be distributed throughout a network or they may be concentrated in centralized data centers.
Advances in centralized data processing centers have resulted in smaller form factors for server devices and an increase in the density of processing units, thereby reducing space requirements for computing infrastructure. One common form factor has been termed in the art a “blade server,” comprising a device built for vertically inserting into a chassis that can house multiple devices that share power and other connections over a common backplane, i.e., a blade center. Slim, hot swappable blade servers, also referred to herein as “blades,” fit in a single chassis like books on a bookshelf. Each blade server is an independent server, with its own processors, memory, storage, network controllers, operating system and applications. The blade server slides into a bay in the chassis and plugs into a mid- or backplane, sharing power, fans, floppy drives, switches, and ports with other blade servers. The benefits of the blade approach will be readily apparent to anyone tasked with running down hundreds of cables strung through racks just to add and remove servers. With switches and power units shared, precious space is freed up—and blade servers enable higher density with far greater ease. With a large number of high-performance server blades in a single chassis, blade technology achieves high levels of density.
A blade based rack uses a common bus for all the blades. This bus is used by the blades to communicate with the management module and also gives access to the external network via special external switch modules. Advanced versions of the server blades include an embedded blade switch. These embedded blade switches provide external connectivity to other units in the server blade, such as a Flexible Service Processor, available from International Business Machines, Corp.
In an advanced server blade having an embedded blade switch, the concept of a “link” differs from the traditional definition. When an external switch module is unplugged from the blade based rack, a bus controller generates a “link down” event to all the blades on the rack. However, because the operating systems on the individual server blades are not directly connected to the external switch module, an Ethernet device driver in an operating system will not receive the “link down” event from the bus controller.
Various mechanisms have been proposed to allow components on the individual server blades to find out about the link loss. However, the proposed mechanisms are based on polling the communications link, which leads to negative performance issues based on the inevitable polling delay. For example, if the operating system is using etherchannel across multiple Ethernet adapters, then etherchannel uses a feature which continuously pings an external reliable host—such as the gateway—to make decisions on failover. If this ping fails, the link is assumed to be lost, and a failover is initiated. However, this pinging method is prone to false link down events, since any loss of connectivity in the network will trigger an unnecessary Ethernet port failover.